Please see your 2014 tax return if you are unsure.
From here forward, if you are filing as 'Married-Joint, please answer ALL questions for BOTH spouses.
Did you work for an employer between Jan 1 and Dec 31 2015 and receive a paycheck during this time and are expecting a W2?
If filing 'Married- Jointly, please answer for BOTH spouses.
If you are unsure if someone can be claimed as a dependant, please open this site in another tab: https://www.irs.gov/uac/Who-Can-I-Claim-as-a-Dependent%3F